Estimation of Radio Refractivity from Satellite-Derived Meteorological Data over a Decade for West Africa

Abstract Radio refractivity, which is the bending of a radio signal as it propagates through media, is very important in works involving terrestrial atmospheric electromagnetic propagation such as point-to-point microwave communication, terrestrial radio and television broadcast and mobile communication system. This study focused on the West African region where it was found that the refractivity varies exponentially with height ( N = N o e H / h ) and from the coast towards the desert: the average surface refractivity ( N o ) for West Africa was found to be around 342 N-units, while the average scale height ( h ) was found to be around 8.01 k m . Generally, the refractivity gradient was found to range between -46.48 and -29.51 N-units/km (k-factor value of between 1.23 and 1.42) across West Africa, splitting the region between sub- and super-refraction. The variation in refraction type was found to follow a seasonal pattern across the West African region, with sub-refraction dominating during the dry season and super-refraction dominating most part in the coastal area during the wet season.